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Running slightly rough when cold and poor hot starting problems on mk1 172



hey guys!

My mk1 172 has gradually developed a running and starting issue. Starts perfectly from cold but then runs with slight miss fire until warm and has intermittent hot start problems.

Would I be correct in guessing that the cause of this is faulty engine coolant temp sensor?

If not then I'd like to hear some expert opinions..

Thanks

:)
 
  53 Clio's & counting
Yes, there is a chance its the cts, but id get the fault codes read just in case mate - iv seen coil packs cause missfires that only miss once their warm, it could also be a plug or lead breaking down
 
  Megane r26
if you can get the resistance values for the coolant temp sensor whip if out an put a multimeter across it an put the sensor in some water with the meter connected with a thermometer so you can check the water temperature an that the resistance readings are right for that tempreture an slowly warm the water an make sure the resistance alters according. But as said it does sound like a cts fault, one of my old saxo behaved the same when it was knackered too
 
Russ, its the other way round....very very slight miss when cold and perfect running when hot.
Doubt dodgy plug or lead would prevent it from starting when hot?

Dan...there looks like 3 wires going onto the sensor im looking at? which one is the CTS? Im looking at gear box side at the back of the head in a seperate block with water pipes going to it? Am i looking at the one for gauge by mistake?

What resistances should i expect?

cheers!
 
  Megane r26
Right, automata doesn't have the resistance value information for this model which is typical but sounds like you have the right sensor. The sensor is a 3 way sensor hence the 3 pins an according the Renault manual 2 are for the coolant temp information an one is for the indication on the instrument panel. But again can't seen to find the values! Is there any idents or numbering on the multiplug or the sensor cause I do have the wiring diagram
 
I have the sensor removed from the thermostat houing now and its a Magneti marelli sensor part number 402 114 02 on the reverse has the numbers PA66GF 13 and the numbers 7700113867 incase anyone needs these for future reference :)
 
well the CTS didnt fix my problem! Gutted!
Code reader next I think!

Take it you dont have to rest ther ECU so the new sensor? Its hould be plug and play right?
 
  Megane r26
Don't like to guess tbh, is it doing it constantly yet or still when warm? The problem could still lye within the ignition system i.e plugs, leads or coilpack. If i lived closer i'd come sort it for ya lol but theres a few hundred miles between us haha
 
does it constant. Have tried it stone cold and at full temp with cooling fan running.

Its a weird one that for sure. The egg smell makes me think its pouring fuel into the exhaust and damaging the cats?

I appricate the offer mate....ill get to it as i spent years messing around with cossies so used to dodgy engine sensors!
 
  Megane r26
Yeah, whip the plugs out too an see what colour they are. Always a good indication.

Ooooo cossies, most my family are or were into fords. Cossies an RS's, good knows what got me into french cars lol
 
  Megane r26
plugs look a paint to get out cos of inlet?

your family will prob know my old saf then...was one of the fastest, did 188 mph at bruningthorpe

There not bad but top part of inlet does have to come off. Maybe but it was proberly best part of 15 years ago when my old man had his saph
 


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